Field of the Invention
The present invention relates to the field of food biotechnology, and more particularly relates to a method for extracting oil from dehydrated Euphausia superba. 
Description of the Related Art
Euphausia superba (Antarctic krill) is a pelagic shrimplike invertebrate that lives in the Antarctic waters. Euphausia superbas live in large schools and feed on minute phytoplankton. It is the largest single biological resource in the world. The water content of fresh Euphausia superba is up to 80%. Currently, most of Euphausia superba are frozen for storage, transport and further process. In this way, the cost of transportation is very huge and the effective transportation payload is relatively low.
Euphausia superba is dehydrated before transportation and oil extraction. The process of dehydration is either under high temperature or high energy-consumption. The traditional solvent extraction of krill oil is accompanied by problems such as high temperature and incomplete desolvation. Supercritical CO2 extraction is an effective method for oil extraction, however, the equipment for supercritical CO2 extraction is pretty expensive and complex to use. Since supercritical CO2 extraction is carried out under a high pressure, there are certain security risks. Other methods for preparing krill oil from Euphausia superba powder, fresh Euphausia superba or frozen Euphausia superba have the following disadvantages: (1) The drying process is high energy-consuming, low efficiency and environment-unfriendly. (2) The process of dehydration or oil extraction is carried out at high temperatures, which results in the oxidation of active ingredients.
To solve the existing problems, the present invention provides a method for dehydrating and extracting oil from Antarctic krill under relatively low temperature in a closed anaerobic environment, thus minimizing the oxidation of active ingredients and eliminating environmental problems caused by solvent volatilization. The oil extraction is performed under an ultrasound-assisted subcritical fluid extraction condition. It uses a short-term ultrasonic approach to generate a “vacuolar effect” in the extraction system so as to increase the contact of the substrate and the solvent. Since subcritical fluid is in gas phase under ambient conditions, high temperature is not needed for desolvation, and the solvent residue problem is minimized.